Tractors used for agricultural purposes and the like are characterized by various hydraulically operated facilities, among which is the three point hitch. This hitch is comprised of three points of attachment for draft tools as circumstances require, a top center hitch and a pair of spaced lower hitches. These three hitches are moveable points of connection which cooperate as a system of levers, and in practice the lowermost pair of hitches involves a pair of draft links that pivot from the tractor frame to support an implement or the like, most often incorporating a transverse implement bar to which the implements are attached. The uppermost hitch also involves a link, all of which articulate freely and are subject to adjustments. Operation of this three point tractor system is by means of a cylinder and piston unit, or the like, operable to articulate the three levers in unison. Although the points are variable as to position, their relationship is set up so as to accommodate an A-frame attachment at pivot points such as to establish a parallelogram with respect thereto, or substantially so. In practice, the A-frame has two lower legs attached to the two lower hitches, and it has an apex attached to the upper hitch. This A-frame is then adjustable vertically by means of raising or lowering the three hitch points and positioning the same with a hydraulic actuator unit therefor. For whatever purpose may prevail, the A-frame and transverse implement bar remain installed as a permanent facility.
With the foregoing in mind, it will be apparent that hydraulics is available on such tractors, to operate the various cylinder and piston means that are involved. Furthermore, it will be understood that space availability for additional features is limited. Obviously, the three point hitch has its great advantage in leveling the implements that are attached thereto, and on occasions the three point hitch is called upon to operate as a lift. However, the three point hitch is per se a short coupled feature and is not far reaching nor adaptable to varied loads and awkward positions thereof. Therefore, it is an object of this invention to provide a boom attachment to the three point hitch, whereby varied load situations are accommodated with facility.
It is the A-frame which characterizes the three point hitch, or an equivalent form thereof. In any case, there are the obvious top center point and spaced lower points of attachment, all of which are extended a short distance from their pivotal suspension points with the tractor frame. Consequently, there is limited space between the tractor frame and the aforementioned A-frame, and it is this space which provides for the accommodation of the attachment herein disclosed. Accordingly, it is an object of this invention to provide a boom attachment to the said A-frame, to be carried thereby and to cooperatively operate therewith to lift loads as circumstances require.
Attachments are most often cumbersome and interfere with other devices, and consequently must be removed when not in use. However, with the present invention the foundation or base of the attachment is permanently installed and ever ready for a boom extension which characterizes the invention. Accordingly, it is an object to provide permancy in an attachment of the character referred to, whereby the tractor is equipped with a lifting boom facility.
It is an object of this invention to provide a three point and lifting boom combination wherein cooperative efforts are employed, and so that the limitations of one device are enhanced by the other. That is, the three point hitch moves vertically while the boom swings through an arc. It is to be noted that the usual winch system of a crane is not required herein, and in essence is replaced, unobviously, by the vertical lift features of the three point hitch. With the present invention, the live line as used with booms and cranes for vertical lifting is replaced with a drop line, and the vertical lift function is provided by vertical movement of the three point hitch and A-frame which supports the instant attachment.